do you think silencers are...

okay here it is my homemade silencer for my air rifle but fitted to my Walther CP99 the first 2 shots are with out and the second 2 are with it uses the design i originally posted[youtube]http://www.youtube.com/watch?v=AwKEgJ8pyBQ[/youtube]

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I work for a company in Los Angles called Ultramet and we deal with Advanced Materials. My company takes Polyurethane Foam coats it in a resin then pyrolizes it and converts it into Reticulated Vitreous Carbon Foam or RVCF. The foam can be molded into 100 ppi which not only is thermally insulating, resistant to thermal shock, but also great for sound attenuation. It has a High temperature capability of 4000ºF and has low thermal conductivity (<1 W/m • K at 3600ºF). The Reticulated Vitreous Carbon Foam has excellent noise attenuation capabilities when sound waves are propagating perpendicularly through the foam. The foam achieved noise reductions of 44 dB/m at 250 Hz and 64 dB/m at 1000 Hz. This foam is used in Aeronautic and Military weapon development applications where silence and heat dissipation is crucial.

I know this is not something just anyone can find at a store. I am just trying to prove there are materials out there that are much better than steel wool to use but they are far and few in between. Using a material in the expansion chamber is perfectly effective. Steel wool is a GREAT substitute if can’t obtain a material like RVCF. Anyway, its overkill if you look at how little heat and thermal shock our cannons produce.

Somebody once compared a spud gun with an internal combustion engine in earlier threads and this comparison is pretty accurate. Let’s explore automobile silencers. Automobile engines are generally constructed with an exhaust silencer unit that is connected with the exhaust gas passageway. These are created to reduce the exhaust noises associated with internal combustion engines without affecting the performance of the engine. They use a dense absorptive steel fibrous material packed into a sound absorption chamber in the muffler. You can research it if you’d like, it all started with U.S. Patent Number 4,396,090. When it was first built they constructed a muffler in which the sound reducing chamber was completely filled with fibrous metal wool. They found the sound attenuation of the design achieved great results but was deemed to expensive to manufacture. This problem was solved soon after, but let’s not get off topic.

I stand firm in believing using a material to absorb some of the heat, shock, and sound would be a great additive to any expansion chamber in a suppressor. Sorry for the long post, but I was just itching to get that off my chest! hehe

Low thermal conductivity? That is the exact opposite of what one is looking for in a suppressor packing material If you wanted the best packing material you would looks towards copper wool or something that sucks up heat quicker.

I forgot to mention that is only the base format for the foam. The Foams are ideal for thermal management applications because they have high surface areas and can be made from materials with high thermal conductivities. We also can impregnate Silicon Carbide as an active heat sink into the foam which has much more thermal conductivity than copper. The actively cooled heat sink can be designed to accept high or low pressure and through its conductivity create an optimal pressure drop, thus helping with sound attenuation.

Sorry I forgot to include that mention in my writings as it was a much needed detail. My apiologies for the confusion.

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" Forget about all the reasons why something may not work. You only need to find one good reason why it will. "

umm ok... that was a bit confusing to read so will someone please answer this question with something very simple. How should i make my suppressor? and how in the world do you glue the baffles on thats how iam confussed like wouldnt air just blow it away. and what filler should i use if i should use any at all. this is for a pneumatic NOT a combustion

Well, if you care about performance, read all 5 pages of this thread, and the other threads on silencers, especially what Rag has to say.If you don't, (which sounds like the case,) here is a rough summary with all of the basics:Make it as big as physically possible. Glue (or what ever) baffles in, as they probably help. it doesn't matter that much where you put them (either the front or the back could be best, but nobody really knows for sure). You should probably also put soft stuff in there, as it may help to dampen the sound. Finally, make it BIG!

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Do not look back, and grieve over the past, for it is gone;
Do not be troubled about the future, for it has not yet come;
Live life in the present, and make it so beautiful that it will be worth remembering.

Doesn't matter where you put them- FALSE. They need to be upfront to draft the air into the expansion chamber which should be located towards the back end of the silencer. (LOOK AT ANY FIREARM SUPPRESSOR)

You should probably also put soft stuff in there, as it may help to dampen the sound-TRUE and FALSE. You need high surface area material that has a high thermal conduction, resistant to thermal shock, and most importantly had GREAT sound attenuation. Any material you can find that meets all 3 is fine. But I assure you, densely packed steel wool is the optimal product you will find easily.

sputnick wrote:I would have to disagree with you, Heat absorbtion is not an effective means of suppression. Even if it is somehow a viable means of reducing noise, which I highly doubt, then it would be completely inefficient, because then the heat from the previous shot would be absorbed into the steel wool, making it less effective with every consecutive shot until given time to cool (me not knowing how long that would be not since I do not make combustion guns or make suppressors for them) but I imagine it would be considerably long seeing as the wool is kept in a confined area with hot gasses

If this were true, suppressors would not be more effective when used "wet" - example from here:

Additives, like grease, oil, water or even snow may enhance the performance of the sound suppressor. Popular known as “wet can”, the effect of these substances cools the expanding gasses. The volume of the gasses then decreases, which have a positive effect on the performance of the sound suppressor. The different substances is only to be used in the amount of one teaspoon full per shot.

Another interesting point about baffles is that their effectiveness can be increased by using springs as opposed to solid spacers, as can be seen in the "Sound Biter" made for airguns and rimfires:

The gasses expend extra energy pushing against the springs, in the same way they would against sound absorbent foam, and this reduces noise levels at the muzzle.

As to porting the outer part of the can, I stand by my words. Airgun silencers are an established commercial product that has been used for decades, and I can't find a single example that has holes other than those on the ends. If it worked better, someone would be using it.

The Weihrauch silencer, one of the best commercially available silencers for airguns, looks like this internally:

It achieves its performance using significant volume, baffles and sound absorbing material similar to J-cloth wrapped around what are effectively plastic hair curlers

lol no thats not mine although thats similar to one i made with a mill, but on youtube you cant upload a .mp3 file so i had to put it into movie maker and just searched silencer- images and there it was. Thats not even a baffle stack its more of a baffle insert